Ilmenite is commonly used as source material for the production of pigmentary titanium dioxide and is found in massive deposits of ilmenite-magnetite in the Adirondack Mountains of New York. As mined, the ore may contain about 32% ilmenite and 35% magnetite with lesser amounts of other materials such as feldspar, garnet, hornblende and the like, these latter materials being sometimes hereinafter referred to generically as silicious materials. The magnetite portion of the ore also contains appreciable amounts of vanadium. A magnetite concentrate comprising essentially iron oxide as Fe.sub.3 O.sub.4, some silicious material and relatively high levels of vanadium is obtained by processing the ilmenite-magnetite ore in successive grinding and wet-magnetic separation operations an ilmenite concentrate being recovered from the non-magnetic tailings by hydraulic classifiers and tables.
The magnetite concentrate so obtained may comprise as high as 65% iron as Fe.sub.3 O.sub.4 and 0.5% vanadium. This concentrate has been treated by the well-known soda-roast method to recover the vanadium. However, the recovered iron is unsuitable as blast furnace feed because of high soda (sodium) contamination.
U.S. Pat. No. 3,615,342 is of interest in that it refers to a soda-roast leaching process for removing non-ferrous metal values including vanadium from iron ore concentrate wherein the iron ore is mixed with soda ash and the mixture formed into pellets which are roasted and then leached to recover the vanadium values as a water soluble sodium-vanadium compound. However, as the patentee points out, the leached pellets so formed include relatively high levels of sodium and hence are unsuitable for use as feed material in blast furnaces; the gist of the invention being reduction in the amount of sodium in the pellets by soaking the pellets in an aqueous solution of calcium chloride for protracted periods of time at 176.degree. F. and then elevating the temperature to as high as 235.degree. F. to remove the sodium values.
U.S. Pat. No. 3,733,193 relates to a technique for recovering vanadium as sodium vanadate from ores such as magnetide using high levels of soda ash, i.e. from 10 to 20%; with or without from 2-15% Al.sub.2 O.sub.3. This patent is, however, concerned only with the percent recovery of vanadium as sodium vanadate from the magnetite and not with the composition of the residual iron oxide product as feed material for blast furnaces in the production of metallic iron.